A376585 a(n) = 2^(2*n - 1) - 2^(n - 1)*(n - 1).

1, 2, 6, 24, 104, 448, 1888, 7808, 31872, 129024, 519680, 2086912, 8366080, 33505280, 134111232, 536641536, 2146992128, 8588886016, 34357510144, 137434234880, 549745852416, 2199002284032, 8796048982016, 35184279814144, 140737295417344, 562949550768128, 2251798974824448

Offset: 0

Author

Peter Luschny, Sep 29 2024

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (8,-20,16).

Crossrefs

Cf. A020522.

Programs

Maple

A376585 := n -> 2^(2*n - 1) - 2^(n - 1)*(n - 1):

Mathematica

LinearRecurrence[{8, -20, 16}, {1, 2, 6}, 27] (* Hugo Pfoertner, Sep 29 2024 *)

Formula

a(n) = [x^n] (-10*x^2 + 6*x - 1)/((2*x - 1)^2*(4*x - 1)).

a(n) = ((24 - 8*n)*a(n - 2) + (6*n - 22)*a(n - 1)) / (n - 4) for n >= 5.